chore: regenerate README (#499)

This PR was generated using Autosynth. 🌈


<details><summary>Log from Synthtool</summary>

```
2021-04-09 18:40:25,456 synthtool [DEBUG] > Executing /root/.cache/synthtool/java-dataproc/.github/readme/synth.py.
On branch autosynth-readme
nothing to commit, working tree clean
2021-04-09 18:40:26,643 synthtool [DEBUG] > Wrote metadata to .github/readme/synth.metadata/synth.metadata.

```
</details>

Full log will be available here:
https://source.cloud.google.com/results/invocations/1bb7d9ad-6f50-41f9-9159-cee8f7933d28/targets

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.github/readme/synth.metadata/synth.metadata

@@ -4,14 +4,14 @@
       "git": {
         "name": ".",
         "remote": "https://github.com/googleapis/java-dataproc.git",
-        "sha": "dc806cf70bb7b5e0c5c255f9e0d5f7221869e5b2"
+        "sha": "81b26b1b38536ab2fc4c52796a19b66646072ccc"
       }
     },
     {
       "git": {
         "name": "synthtool",
         "remote": "https://github.com/googleapis/synthtool.git",
-        "sha": "60fc32cc950c20cfdd774b846a4a7dc5d1e4d0ef"
+        "sha": "1f5e6bc8dc8e3661ee550905fc070e55e1b6cea1"
       }
     }
   ]

README.md

@@ -8,6 +8,9 @@ Java idiomatic client for [Dataproc][product-docs].
 - [Product Documentation][product-docs]
 - [Client Library Documentation][javadocs]
 
+
+
+
 ## Quickstart
 
 If you are using Maven with [BOM][libraries-bom], add this to your pom.xml file